1. Field of the Invention
The present invention relates to a method of assembling a vehicle frame with components constructed from hydro-formed tubular members without a framing fixture.
2. Background Art
One method of vehicle frame assembly is referred to as a balloon build method in which the vehicle frame is established by connecting a stamped metal front body section with a stamped metal rear body section. This process maintains several advantages which include a smaller manufacturing floor footprint and less manufacturing tooling requirements. However, this method of assembly presents some unsatisfactory disadvantages such as an unacceptable side door opening dimension variation, wind noise, and water leakage. Dimensional errors usually occur in one of two fashions. First, the front and rear components are constructed in a metal stamping process. Metal stamping processes suffer from the need to allow tolerances that may stack-up from part to part and cause a variance in vehicle lengths. Second, variance in vehicle length may also occur if the front and rear components of the vehicle frame are not correctly assembled prior to welding.
Another method of vehicle frame assembly is known as the multi-piece body side build wherein a plurality of smaller components are assembled and joined together to form the overall vehicle frame. This method improves the side door opening dimensions and provides more acceptable cross car dimensions. However, because many of the smaller components are constructed using a metal stamping process, acceptable variations known as tolerances occur for each of the components. These component variations result in tolerance stack-up when the components are joined together. Due to tolerance stack-up, this method is not able to rectify the wind noise or water leakage problems that had occurred in the balloon build method. Also, this process increases the manufacturing tool and floor space required to accommodate assembling the smaller components.
Another method of vehicle frame assembly is known as a one-piece body side method. This process requires the structural end item components to be added to the mainline body side process. Larger portions of the vehicle such as the body side door opening panel, roof, and underbody are assembled to the mainline body. This process eliminates the gaps found in both the previous methods. Also, this method virtually eliminates any wind noise or water leakage caused by tolerance stack-up or imperfect joining of body parts. However, this process requires an extremely large investment in body side fixtures to assemble large components, such as a body side door opening panel assembly.
The previously demonstrated methods improved on vehicle design. The balloon build method offers simplicity and low cost to build, but presents end result errors in how the vehicle body is joined together. Furthermore, the multi-piece body side build method improves side door opening dimensions, but does not solve the concerns of wind noise and water leakage. Lastly, the one-piece body side method aids in solving many manufacturing process problems, however, the investment cost and amount of manufacturing floor space are substantial disadvantages.
The above problems and others are addressed according to the method of the present invention.